Hydraulic System

Question 1

The #3 Hydraulic pump failed in flight. After starting the APU, how is the APU accumulator recharged?

Answer 1

Wait till the WOW is enabled after landing and the APU ACCUM LOW segment will automatically turn on the AC Powered (#1 AC Pri Bus) Ground Checkout Pump.

Question 2

What systems can the #3 Hyd system pressurize?

Answer 2

1. Back up for the # 1 and # 2 Hyd systems
2. Provides pressure for operation of the landing gear, cargo ramp, and recharging the APU accumulator)

Question 3

What is the normal (green) operating pressure range for hydraulic system?

Answer 3

3500-4200 psi

Question 4

What is the green range of the Utility Hydraulic system in the depressurized mode?

Answer 4

2000 +/- 1000 psi

Question 5

What systems are pressurized by the No 1 Hydraulic pump?

Answer 5

1 SAS, #1 PRI servo, and #1 TR Svo,

Question 6

What systems are pressurized by the No. 2 Hydraulic system?

Answer 6

2 SAS, #2 PRI servo, #2 TR Svo, and the Boost

Question 7

What does the Caution HYDR FAN FAIL indicate?

Answer 7

The AC powered Fan in each Heat Exchanger that cools the # 1 and #2 Hyd system oil are inoperative.

Question 8

How is fluid distributed throughout the entire system after it leaves the Hyd. Pump?

Answer 8

Transfer Modules for the No 1 and 2 system and Utility Module for the #3 system.

Question 9

What does the caution No 1 or No 2 RSVR LOW indicate? How does the system respond to this condition?

Answer 9

Fluid reservoir levels are below the normal limits (less than 50% remaining)

Leak Detection and Isolation (LDI) will close the affected tail rotor shutoff valve and close the affected backup shutoff valve

Question 10

If the leak was not in the tail rotor plumbing (Aft of the tail rotor shutoff valve) what would you expect to happen next.

Answer 10

Affected Hyd pump fail caution light followed by a pressure loss for each system the pump pressurized. (MR SVO, SAS, T/R, and Boost for #2 system)

Question 11

What is the function of the Backup Shutoff Valve and how does it operate?

Answer 11

Prevents unwanted shuttling of Hydraulic fluid between the Primary systems (#1 and 2) and the 3 system during engine start and shutdown.

Upon Engine start, DCU’s close the backup shutoff valves with first engine above 15% NG and reopens the valves when NR goes above 50%.
During Engine shutdown, DCU’s again close when NR goes below 50% and reopens 2 minutes after the last engine NG goes below 15%.

LDI will close the backup shutoff valve to isolate the NO. 3 Hydraulic system from a leaking primary system.

Question 12

After engine shutdown the pilot tries to move the flight controls to better position them to the center. The flight controls will not move. What may be the problem?

Answer 12

Backup shutoff valve closed (for 2 minutes after last engine NG goes below 15%.
Rotor stopped with Ground pump in the off position.

Question 13

List the 5 independent hydraulic systems.

Answer 13

Hydraulic systems 1,2 & 3
Rotor brake
Wheel brake

Question 14

If a hydraulic system loses hydraulic pressure, can the other system be shut off?

Answer 14

No, an interlock prevents this

Question 15

1. If Hyd #2 system has a leak past the tail rotor shut off valve, when will the LDI be activated.
2. What caution segments and system pressure will be observed in the cockpit?
3. Will there be any control degradation?

Answer 15

1. At 50% level in Reservoir
2. HYD RES #2 Low, TR 2 Servo, Normal system pressure
3. No degradation in controls

Question 16

If the #2 Hydraulic system has a leak prior to the tail rotor shut off valve, what caution segments and system pressure will be observed in the cockpit?
Will there be any degradation in the controls?

Answer 16

Same LDI response, however, as the leak is before the shut off valve, all oil will be lost is Sys #2 and therefore the pump will also fail.
HYD 2 RSVR LOW, TR SVO 2 PRES, MR SVO 2 PRES, HYD 2 PUMP FAIL, SAS 2 PRES, BOOST PRES

There will be an increase in control forces with the loss of boost

Question 17

What temperature limits apply to the Hydraulic System?

Answer 17

Temperature above 110°C will activate a HYD 1(2) TEMP ALERT

Temperature above 135°C will activate a HYD 1(2) TEMP LIMIT

Question 18

What conditions must be present to perform the Hydraulic LDI test?

Answer 18

Aircraft must be Weight On Wheels
AC power available
HYD Ground Pump on
Rotor Brake on

Question 19

Does the hydraulic system have a filter bypass capability in the event of a clogged filter?

Answer 19

Yes, but only on the Return filters to prevent hydrostatic lock